rebuild the engine in Rust

Python was never the house language here: the mw-* desktop surface it came
from is 39 bash scripts and was exactly one Python script, the one this was
extracted from. What it cost was distribution, a widget dependency that
needed pipx and a Python floor, and 24ms of interpreter startup before a line
of the program ran.

The port is verified rather than asserted. Both implementations were run over
199,446 day-records, 26 jurisdictions across 21 years, with every field of
every record required to match; the JSON, the iCalendar and 480 renderings of
the text output are identical too. examples/dump.rs is the harness.

What the type system actually buys, which is less than the usual claim and
more than nothing:

  - Level is an ordered enum, strictest first, so  reads as 'a is
    stricter' and relaxed_to() is the one place a feast can lift a fast. No
    rule can get the direction backwards.
  - Date is a newtype over the Julian Day Number and JulianDate is a separate
    type, so a civil date and an ecclesiastical one cannot be mixed up. That
    confusion is the single most common way calendar code goes wrong.
  - Octets is a newtype in the iCalendar folder, because the bug it replaced
    counted characters against a limit RFC 5545 states in octets.
  - Movables is a struct, not a map, so a mistyped key is a compile error
    rather than a None at the far end of the program.

Of the six defects an adversarial review found in the Python, exactly one had
a shape a type system would have caught. The rest were logic, and the tests
came with them.

The menologion is compiled in with include_str!, so the binary answers on its
own: 930KB, no runtime, 1.2ms to start against Python's 36ms.

pyproject.toml

@@ -1,43 +0,0 @@
-[build-system]
-requires = ["setuptools>=64"]
-build-backend = "setuptools.build_meta"
-
-[project]
-name = "typikon"
-version = "0.1.0"
-description = "The Orthodox liturgical day — feasts, seasons and the fast, computed rather than fetched"
-readme = "README.md"
-license = { text = "GPL-2.0-only" }
-requires-python = ">=3.9"
-authors = [{ name = "funkpower", email = "funkpower@pumpin.online" }]
-keywords = ["orthodox", "liturgical", "calendar", "byzantine", "pascha",
-            "menologion", "typikon", "fasting"]
-classifiers = [
-  "Development Status :: 4 - Beta",
-  "Environment :: Console",
-  "Intended Audience :: End Users/Desktop",
-  "License :: OSI Approved :: GNU General Public License v2 (GPLv2)",
-  "Programming Language :: Python :: 3",
-  "Topic :: Religion",
-  "Topic :: Utilities",
-]
-dependencies = []
-
-[project.optional-dependencies]
-dev = ["pytest>=7"]
-
-[project.urls]
-Homepage = "https://git.pumpin.online/funkpower/typikon"
-Source = "https://git.pumpin.online/funkpower/typikon"
-
-[project.scripts]
-typikon = "typikon.cli:main"
-
-[tool.setuptools.packages.find]
-include = ["typikon*"]
-
-[tool.setuptools.package-data]
-typikon = ["data/*.json", "data/LICENSE"]
-
-[tool.pytest.ini_options]
-testpaths = ["tests"]